Plate heat exchangers provided with gaskets normally comprise a plate package of heat exchanger plates disposed adjacent to one another. Gaskets are disposed between the heat exchanger plates. The plate package may also formed by heat exchanger plates that are permanently joined together in pairs to form so-called cassettes, e.g. by welding or brazing, with gaskets placed between the respective cassettes. The gaskets are accommodated in gasket grooves formed during the form-pressing of the heat exchanger plates. Plate heat exchangers further comprise inlet and outlet ports, which extend through the plate package, for two or more media.
Heat exchanger plates are normally made by form-pressing of sheet metal and are disposed in the plate package in such a way as to form first plate intermediate spaces, which communicate with the first inlet port and the first outlet port, and second plate intermediate spaces which communicate with the second inlet port and the second outlet port. The first and second plate intermediate spaces are disposed alternately in the plate package.
The design of heat exchanger plate for plate heat exchangers aims to use as much as possible of heat transfer or heat exchange area for the heat exchange between two or more media, but it also needs take in account how the gasket can be applied on the heat exchanger plate to be securely fastened and to fulfil its seal functionality.
Different designs of the heat exchanger plate and the associated gasket are known in the art. E.g. is a plate heat exchanger known from U.S. Pat No. 5,070,939, where the heat exchanger plate is provided with a gasket groove having a corresponding gasket with nubs which glued to the gasket groove. The nubs serving as indicators of where the glue should applied. In another prior art document, GB-A-668905, the heat transfer area has been alternately retracted along the transport direction to create increased turbulence of the media. In U.S. Pat No. 5,927,395, WO-A1-00/77468 and WO-A1-2005/045346 are shown other solutions on how to fasten the gasket to the heat exchanger plate by clamping the gasket around the plate edge and by forming the gasket groove.
The drawbacks with the above solutions are that they require a lot area along the heat exchanger plate edges to be applied and thereby the potential heat exchange area is reduced. Further the design of the clamping means is rather complicated.